The Development of Linguistic Skill in Twins, Singletons with Siblings, and Only Children from Age Five to Ten Years was first published in 1937.This book constitutes a detailed analysis of 50 remarks obtained under a standardized situation from each of 436 children between the ages of 5 1/2 and 9 1/2 years.The investigation in no sense duplicates former ones. It deals with children of school age and consequently emphasizes such phases of language development as the use of complex sentences and slang and grammatical errors. The connection between good articulation and the development of language ability is stressed.